1. Technical Field
This invention relates to an image pickup device and an image pickup method for photographing an image in a wide dynamic range.
2. Related Art
A digital still camera installing a solid-state image sensing device such as a CCD-type image sensor or a CMOS-type image sensor involves a problem in that the dynamic range of a picked-up image is narrow because the saturation charge amount of each pixel is small.
Thus, technology development for widening the dynamic range of a picked-up image advances. For example, a related art described in JP-A-2007-235656, a large number of pixels installed in a solid-state image sensing device are separated into a first pixel group shaped like checkers or every other row and a second pixel group shaped like checkers or every other row, one pixel group is exposed for a long time, the other pixel group is exposed for a short time, signal charges detected by the pixel groups are added and combined, whereby the dynamic range of a picked-up image is widened.
However, the related art has a problem in that it is suited for widening the dynamic range of a still image, but is hard to widen the dynamic range of a moving image at a high frame rate.
A larger number of pixels of a recent solid-state image sensing device proceed and it is normal to install 1000000 pixels or more. In such a solid-state image sensing device, each pixel is made finer and thus the dynamic range further becomes narrow; this is a problem.
Further, for example, for the CCD type, it is necessary to provide a transfer path of signal charge in addition to a light reception part of each pixel (photoelectric conversion element) on a solid-state image sensing device chip and to widen the light reception part area as much as possible, the charge transfer passage becomes narrow. Thus, formerly, progressive (non-interlace) read of reading all at the same time the detected signal by each pixel of a solid-state image sensing device is normal. In recent years, multifield (interlace) read has become mainstream as in JP-A-2003-32555 and accordingly it takes time in reading a signal. This means that it takes time in reading a moving image at a high frame rate.